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Field Replaceable Unit Isolation by Diagnostic Hardware

IP.com Disclosure Number: IPCOM000051245D
Original Publication Date: 1982-Aug-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Adair, JG: AUTHOR [+3]

Abstract

In order to identify a failing field-replaceable unit (FRU) in a multicard microprocessor system, all signals external to the processor card which are capable of stopping execution of power-on diagnostic software are blocked, thereby isolating the processor card. Then if the diagnostics successfully execute for the processor card, the external signals are selectively enabled, one FRU at a time, so that it is possible to identify a failing FRU through the diagnostic sequence. However, the complexity of direct memory access (DMA) and interrupt hardware makes determination of the failed FRU very difficult at card boundaries.

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Field Replaceable Unit Isolation by Diagnostic Hardware

In order to identify a failing field-replaceable unit (FRU) in a multicard microprocessor system, all signals external to the processor card which are capable of stopping execution of power-on diagnostic software are blocked, thereby isolating the processor card. Then if the diagnostics successfully execute for the processor card, the external signals are selectively enabled, one FRU at a time, so that it is possible to identify a failing FRU through the diagnostic sequence. However, the complexity of direct memory access (DMA) and interrupt hardware makes determination of the failed FRU very difficult at card boundaries.

By adding hardware to block external DMA and interrupt requests and also drive the same internal paths, it is possible to check the processor card hardware independent of the external devices and adapters. Sampling the external DMA and interrupt requests to verify valid external inputs also helps isolate the failures. These greatly improve the probability of correctly identifying the failed FRU when a DMA or interrupt failure occurs.

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